Recent advances in behavioral neuroscience research have permitted investigation of the relations between developing areas of the neocortex and emerging behavioral skills. There is evidence which suggests that while the frontal cortex is among the last areas of the brain to mature, it may subserve important functions during the period of infancy. One potential method for exploring brain/behavior relations is the measurement of scalp recorded brain electrical activity (EEG). Recent conceptual and computational advances have led to the use of the EEG as a measure of both regional development and of the emerging cortico-cortical connections. The purpose of the present study is to extend, into the second year of life, basic research on the maturation of the EEG and its relation to specific cognitive and language behaviors. It is our intention to chart developmental changes in a subset of cognitive and language competencies and to relate these changes to specific parameters of the EEG. We will complete a longitudinal study of 48 infants, beginning at age 14 months, and will see them every two months (14, 16, 18, 20, 22, and 24 months of age). At each age we will assess infant performance on tasks designed to tap frontally and non-frontally mediated competencies. In addition, we will assess the emergence of infant self-regulatory skills and have parents of the infants complete a standardized language assessment questionnaire. We will also record multi-lead EEG. Our aims include documenting changes in brain electrical activity-across the second year of life and investigating the associations between EEG changes and cognitive, language, and self-regulatory development. Enhanced understanding of these processes and their interrelationships will provide an important window into understanding cognitive-neuro development in the second year of life. It may also be of importance in understanding the cognitive, language, and self-regulatory development of atypical populations.